Using the unique data resources of the Rochester Epidemiology Project, we have designed a population-based retrospective cohort study to examine the risks and complications of silicone breast implants among 749 Olmsted County, Minnesota, women who received these devices between 1964 and 1991, and 1498 control women who did not receive such devices.

In this paper, we present data describing the populationbased trends in the utilization of these devices from 1964 to 1991.

In addition, we discuss the case ascertainment, outcome assessment, and reliability of the data collection for the outcomes study.

The utilization of breast implants increased markedly over the past 30 yr with the rate of new implants per 100,000 women (=15 years of age) rising from 3.5 in 1964 to 95 in 1979, remaining stable thereafter.

The prevalence of breast implants among Olmsted County women =15 years of age on 1 January 1992 was approx. 1%. An examination of the characteristics of these women reveals that recent utilization of breast implants has increased more rapidly among rural than among urban women, that the proportion of women receiving implants for breast cancer mastectomy reconstruction has increased in recent years, and that the great majority of women receiving implants are married at the time of implant.

These trends also revealed that the average age of women who receive implants is rising and that in more recent years both much younger and much older women are receiving implants.